/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.io.gcp.bigquery;



import com.bff.gaia.unified.sdk.coders.VoidCoder;

import com.bff.gaia.unified.sdk.transforms.*;

import com.bff.gaia.unified.sdk.transforms.Create;

import com.bff.gaia.unified.sdk.transforms.DoFn;

import com.bff.gaia.unified.sdk.transforms.PTransform;

import com.bff.gaia.unified.sdk.transforms.ParDo;

import com.bff.gaia.unified.sdk.transforms.View;

import com.bff.gaia.unified.sdk.values.PCollection;

import com.bff.gaia.unified.sdk.values.PCollectionView;



/**

 * This transforms turns a side input into a singleton PCollection that can be used as the main

 * input for another transform.

 */

public class ReifyAsIterable<T> extends PTransform<PCollection<T>, PCollection<Iterable<T>>> {

  @Override

  public PCollection<Iterable<T>> expand(PCollection<T> input) {

    final PCollectionView<Iterable<T>> view = input.apply(View.asIterable());

    return input

        .getPipeline()

        .apply(Create.of((Void) null).withCoder(VoidCoder.of()))

        .apply(

            ParDo.of(

                    new DoFn<Void, Iterable<T>>() {

                      @ProcessElement

                      public void processElement(ProcessContext c) {

                        c.output(c.sideInput(view));

                      }

                    })

                .withSideInputs(view));

  }

}